Shalom, Why specifically do they whisper to her as opposed to speaking normally?
Thank you very much for your help,
Avraham Sacks, Ramat Beit Shemesh
Shalom R' Sacks,
On a basic level, I would have assumed that the answer is because we don't want her to feel undue pressure to fast if she's not really able to do so. Thus, we do not use a normal voice, because she might feel compelled to fast when she might not actually be able to handle it. Instead we whisper to her, and thereby she can decide on her own if her body can handle continuing to fast or not.
But subsequently Rabbi Reuven Subar pointed out to me that the Sefer Kol Eliyahu writes (in the name of the Kinmon Bosem on the Ein Yaakov, Koenigsberg edition) that Rebbi Chanina cited Tehilim 58:4. Shortly after that point in Tehilim (58:6), the Posuk itself make reference to "one who does not heed the voice of Melachshim". Therefore, according to this interpretation, the strategy of initially whispering -- rather than talking at a normal volume -- was reflective of the allusion he saw in the verse, and the implication it bore regarding the wicked character of Shabtai Atzar Peiri who later emerged.
Warmest regards,
Yishai Rasowsky
Upon thinking more about your excellent question, it occurred to me that the critical issue regarding this Lachash may not be just whether it spoken quietly versus aloud. The point may be that it is a supernatural formula to communicate with and calm the fetus. So, the Lachash is not necessarily to simply inform the mother in a quiet voice that it's Yom Kippur, but it's an attempt to relax the baby through the incantation.
If we locate cross references where this term Lachash is used, there are contexts where it clearly does mean whisper. (For example: II Shmuel 12:19, regarding David's son; Tehilim 41:8, regarding evil conspirators; Rambam Hilchos Talmud Torah 3:12 and Eruvin 54a, regarding learning in a quiet voice; Rambam, Hilchos Krias Shema 1:4 and Shulchan Aruch Orach Chayim 101:2, regarding how to recite certain portions of Tefilah.) But there are places -- even aside from Tehilim 58:6 which we examined above -- where the connotation does appear to mean incantation with no relation to whispering per se. (For example: Mishnah Sanhedrin 10:1, regarding the attempt to heal a wound; Koheles 10:11 and Yirmyahu 8:17, regarding protection from a snake bite; Yeshayah 3:20, regarding ornamental garments.)
Yishai Rasowsky